The invention relates to a Voice over IP (VoIP) network performance monitor.
Packet-based networks, in particular, VoIP networks, are rapidly emerging as a viable alternative to traditional telephony (that is, circuit switched networks). VoIP is viewed as an attractive option for voice transport in that it allows live voice conversations to be integrated with existing IP data and image applications. To be a truly competitive alternative, VoIP must emulate the performance of traditional telephony and do so using a protocol that was optimized for data traffic. The characteristics of data traffic are quite different from those of voice traffic.
Unlike data traffic, voice traffic is extremely intolerant of delay and delay variation (or “jitter”), as well as, packet loss. Much work has been done in the area of packet delivery to provide end-to-end Quality of Service (QoS). Service level agreements (SLAs) for VoIP, like those for conventional data IP networks, tend to be based on conventional data network metrics—that is, guaranteed service levels are expressed solely in terms of packet level performance, for example, packet loss, jitter, and round-trip delay.
Traditional network performance measurement tools use Packet InterNet Gropers (PINGs) to measure packet loss, jitter and round-trip delay. However, VoIP networks are packet-based networks that transmit data in one-way steady streams of User Datagram Protocol (UDP) packets, which PINGing tools cannot simulate. In addition, traditional network monitoring systems accept performance data that has been averaged over an extended period of time, such as a day or a month. While such measurements are acceptable for data transmissions, which are typically TCP in nature, the real-time nature of VoIP service makes daily and/or monthly averaging of performance results inaccurate in representing a VoIP network user's experience of the service.